If someone ever decided to make a documentary entitled “Capturing the Jareckis,” the family in question would look a lot more like a 1970s version of J. D. Salinger’s Glass family than the Friedmans. It would feature a brainy group of serial overachievers, a commitment to film and social justice and a politically engaged soundtrack by Pete Seeger, Bob Dylan and Phil Ochs.

Aside from disparate documentary urges, an upbringing in expensive suburbs and several male offspring, there is very little overlap between the Friedmans, the dysfunctional Great Neck, N.Y., family whose sex abuse case provided the basis for Andrew Jarecki’s Oscar-nominated documentary, “Capturing the Friedmans,” and Mr. Jarecki’s family, which includes high-powered parents and two other accomplished filmmaking siblings.

What is remarkable, almost grist for someone else’s film or novel, is the degree to which a quarter-century after the guilty pleas by Arnold Friedman and his son Jesse, and a decade after his film was finished, Mr. Jarecki remains obsessively committed to Jesse Friedman’s exoneration.

Four days after the release of a 155-page report in which the Nassau County district attorney, Kathleen M. Rice, said firmly that Jesse Friedman had been properly convicted and did not deserve to have his status as a dangerous sex offender overturned, Mr. Jarecki found himself back in court with Mr. Friedman’s lawyer, Ron Kuby, pursuing a new round of appeals.

In more than a few places, the report by Ms. Rice’s review team and its advisory panel of outside experts seemed as focused on reviewing Mr. Jarecki’s film as on parsing points of law and fact.

“The Review Team committed itself to follow the facts wherever they might lead, and found that the whole truth diverged significantly from the edited version of events portrayed in the film,” Ms. Rice’s report concluded.

Mr. Jarecki, 50, strongly disagrees, noting that in the film and beyond it, he has interviewed 19 students of the computer classes in which Arnold and Jesse Friedman were accused of molesting boys in the 1980s, more than Ms. Rice’s review team did. He called her report “a 155-page rehashing of old evidence and the development of new evidence based on discredited sources, hearsay and the admission that they didn’t really talk to the witnesses.”

He characterized the case as one of coerced confessions and a tainted investigation.

Mr. Jarecki has pursued the case with such dedication in part because he can.

He was one of the founders of Moviefone, which began as a telephone movie-listing service and was sold for hundreds of millions of dollars in 1999, leaving him with a fortune large enough to serve as a financial cushion that most aspiring filmmakers can only dream of.

But Mr. Jarecki’s remarkable persistence is also a reflection of his family DNA and a harrowing personal journey that has played a role in turning a film into a cause.

His father, Henry Jarecki, is a psychiatrist, businessman and movie and theater producer, who was a pioneer in using computers for commodities trading. His mother, Gloria Jarecki, was a film critic for Time magazine. His brother Eugene Jarecki and half-brother, Nicholas Jarecki, are both successful filmmakers. Another brother, Thomas Jarecki, is a finance executive.

For all of them, interest in film and a passion for liberal causes were central threads of family life, pursued through their work and a family foundation all four brothers and their families contribute to.

“My father is sort of a Teutonic taskmaster who believes in hard work; from him I get that sense that if you don’t finish that brief you’re not staying up late enough,” said Andrew Jarecki, who grew up in Rye, N.Y., lives in Manhattan and has three children. “My mother brought a lot of humanity to that, a passion for fairness. Our family really gets our energy from trying to outsmart each other in arguments. We’re not a family that plays ultimate Frisbee together.”

His first film project morphed from a look at children’s party entertainers into the dark recesses of “Capturing the Friedmans,” and though the film has a haunting ambiguity, Mr. Jarecki became increasingly convinced over time that Mr. Friedman was not just unfairly convicted, he was innocent. As he worked on new projects, including fictional and nonfictional takes on another troubled family, the Dursts of New York, he has brought his father’s energy and both parents’ passion for social justice to Jesse Friedman’s case.

Mr. Kuby, Mr. Friedman’s lawyer, said that if he had to pay investigators on the open market for all the work done on the case by Mr. Jarecki and his investigators, it would have cost him $20 million.

“Filmmakers make their film, and then they move on to whatever they’re doing next,” Mr. Kuby said. “No one is still there 10 years later because they think it’s the right thing to do.”

Mr. Jarecki said it had been worth it, particularly the interviews. He talked with former students — some complainants, some not — who were in the classes where flagrant abuse, including sodomy, allegedly took place in front of the others; they told him they had never seen any of it and did not believe it had happened. (The review team took issue with his characterization of some of those interviews.) And after a while, Mr. Jarecki said, the case against Jesse Friedman, who served 13 years in prison, seemed so absurd to him that moving on no longer seemed an option.

“The simplest answer,” he said, “is that you have a responsibility because you’ve done the digging, and you’re probably the only person who has this information, and you can’t die with this level of information.”

Those words had an eerie resonance.

In recent years, both he and his wife, Nancy, have faced life-threatening illnesses. She had an aneurysm and he had four operations, the last of which left him hospitalized for several weeks in 2012. Still, each morning he could, he pursued the Friedman case from his hospital room. He said the experience left him more convinced that he had an obligation to do work that mattered, not only projects that appealed to him.

Of course, being dedicated is no guarantee of being right. Ms. Rice, who has had a contentious relationship with Mr. Jarecki, said the artistic license he had in making a film did not make it a fair investigative document.

“There’s no question that at the end of the day a more thorough, transparent view of the evidence was presented in the report than was presented in the movie,” she said.

And Fran Galasso, former head of the Nassau County Sex Crimes Unit, which investigated the case, said that Mr. Jarecki had misled her in making the film, and that both the film and his subsequent efforts ignored the pain suffered by victims of the Friedmans.

“I think he made an interesting film, but not an honest film,” Ms. Galasso said. “It was not a true representation of what actually occurred, and over time he became an advocate. He became so intent on proving this guy’s innocence that he went way off the grid.”

But Mr. Jarecki said the real casualties of the case were the families still haunted by crimes that he believed never occurred, and the integrity of the police and the justice system, particularly during an era awash in child sexual abuse cases that eventually fell apart.

He may face long odds in trying to make that case in court, but clearly he has not finished trying. “It just feels like unfinished business,” he said, “and I have to stay until it’s finished.”

A version of this article appears in print on , Section A, Page 15 of the New York edition with the headline: 1980s Child Sex Case Is a Cause He Cannot Drop. Order Reprints | Today’s Paper | Subscribe